Extract a column from text file - Python

Question

I'm a beginner py.

I need to extract the contents of column 12 from a huge flat text file every time a certain word is found within the text file (similar to awk '{print $12}' in Bash) in a Python script.

So far I have (example, not real code):

word = a_word
for a_word in data:
   column12 = data.split()
   print(column12[11])

I assumed that I should start counting from 0 as opposed to 1, though I very well may be incorrect.

Also, is a for loop correct for this type of code?

Thanks!

What format is your data in? Could you post a row or two of sample data? — Madison May
– Madison May, Commented Aug 20, 2013 at 0:10

Martijn Pieters · Accepted Answer · 2013-08-19 21:47:04Z

8

Loop over the open file object:

with open('somefile') as infile:
    for line in infile:
        print(line.split()[11])

So, yes, use a for loop and use 0-based indexing.

answered Aug 19, 2013 at 21:47

Martijn Pieters

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2 Comments

user3964336 Over a year ago

if we need to split 2 columns ? I tried print(line.split()[1][2]) It says print(line.split()[0][1]) IndexError: string index out of range

Martijn Pieters Over a year ago

@SitzBlogz: str.split() returns a list object. If you need two columns from that, then assign the output of line.split() to a variable, and pick out the two elements you wanted from that list.

Madison May · Accepted Answer · 2013-08-20 02:22:49Z

1

If the columns are text files with delimiter (i.e. space or comma) separated values, you might want to look into python's csv module: http://docs.python.org/2/library/csv.html

edited Aug 20, 2013 at 2:22

answered Aug 20, 2013 at 0:04

Madison May

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1 Comment

martineau Over a year ago

Fields in csv files can be separated by delimiters other than comma, so that not a requirement. So, I agree using it should be considered.

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